In the telecommunications field, particularly in long distance networks, long distance network providers continually strive to increase the traffic carrying capability of their transmission medium. For example, since fiber optic cables have increased bandwidth over known twisted pair or copper wire cables, fiber optic cables are used increasingly for connecting network stations and other network elements. As a result, a greater number of stations or network elements can be connected over a fewer number of fiber optic cables, as opposed to prior cables.
Unfortunately, if one or more of the fiber optic cables fail, massive disruption of services to a large number of network customers and users can result. Network service providers or telecommunications carriers therefore strive to quickly and economically restore traffic effected by these disruptions or "outages." Restoring network outages generally requires four steps: (1) detecting the network failure, (2) isolating the location of the failure in the network, (3) determining a traffic restoral route, and (4) implementing the restoral route. Network restoration must be executed quickly to ensure minimal interruption of network traffic. Therefore, nearly all telecommunications carriers wish to restore traffic within a few seconds or less. The telecommunications carriers typically restore the highest priority network elements first, and as many of such elements as possible within a short period of time.
Currently, telecommunications carriers simulate possible failures, determine restoral routes, and develop a "pre-plan" by collecting large amounts of data reflecting the logical topology of the network. The collected data is often retrieved from network engineering databases which reflect the logical construction of the network, such as indicating the connections and paths of all network traffic trunks. An engineer or network analyst analyses the collected data, compares the collected data to the geographic or physical layout location of the network, and then generates the pre-plans therefrom. Since the pre-plans are developed prior to any failure in the network, when a failure does occur, a plan already exists for restoring traffic affected by the failure. In general, a pre-plan corresponds to a segment of the network that can incur a failure. If that segment fails, then the corresponding pre-plan is retrieved, and its restoral route implemented.
To determine where in the network a failure has occurred, a central location often receives various alarms from the network, which are generated in response to the failure. With the aid of numerous algorithms performed to correlate the various alarms based on trunk topology, the analyst must then match the alarms to a physical network topology to isolate the location of the failure within the network. After locating the failure, the analyst can then identify the appropriate pre-plan. For example, by locating the failure on a physical map of the network, the analyst can then identify an alternative route that restores all failed traffic, without sacrificing other traffic or creating new outages. Locating a failure within the network requires extensive processing, particularly with large networks. Such extensive processing necessarily requires processing time, and therefore increases the delay in restoring the network following the failure.
Telecommunications carriers have handled network outages by simulating different failure scenarios in advance. Based on the scenarios, the telecommunications carriers establish scenarios with appropriate instructions (or pre-plans) that can be used at various stations of the network to establish restoral routes to recover from the network outage. Since the number of possible failures in a network necessarily increases as the size of the network increases, a large number of pre-plans are required. Furthermore, since technological improvements allow network topologies to change relatively quickly and easily, and as a network grows, such networks are not static. As a result, pre-plans must be continually be reevaluated, and new pre-plans created.